Transport refrigeration system with air temperature control

ABSTRACT

A method for air temperature control within a cargo compartment of a transport unit using a transport refrigeration system (TRS) that includes a thermal accumulator having a phase change material (PCM) provided therein is provided. The thermal accumulator is disposed in a thermal accumulator compartment and the cargo compartment is separated from the thermal accumulator compartment via a climate controlled barrier. The method includes a controller receiving, via one or more temperature sensors, temperature data within a cargo compartment of the transport unit from. The method also includes determining a temperature within the cargo compartment based on the temperature data. Also, the method includes determining a temperature stratification within the cargo compartment based on the temperature data. Further, the method includes operating the TRS in an active operation mode when the temperature within the cargo compartment is greater than a temperature set point.

FIELD

Embodiments of this disclosure relate generally to a transport refrigeration system (TRS) including a thermal accumulator or thermal accumulator module having a phase change material (PCM). More specifically, the embodiments relate to air temperature control of a TRS with a thermal accumulator or thermal accumulator module having a PCM.

BACKGROUND

A transport refrigeration system (TRS) is generally used to control an environmental condition such as, but not limited to, temperature and/or humidity of a transport unit. Examples of transport units include, but are not limited to, a container on a flat car, an intermodal container, a truck, a boxcar, or other similar transport unit (generally referred to as a “refrigerated transport unit”). A refrigerated transport unit is commonly used to transport perishable items such as, but not limited to, produce, frozen foods, and meat products. Generally, the refrigerated transport unit includes a transport refrigeration unit (TRU) that is attached to a transport unit to control the environmental condition of an interior space within the transport unit. The TRU can include, without limitation, a compressor, a condenser, an expansion valve, an evaporator, and fans or blowers to control the heat exchange between the air inside the interior space and the ambient air outside of the refrigerated transport unit.

SUMMARY

Embodiments of this disclosure relate generally to a transport refrigeration system (TRS) including a thermal accumulator or thermal accumulator module having a phase change material (PCM). More specifically, the embodiments relate to air temperature control of a TRS with a thermal accumulator or thermal accumulator module having a PCM.

That is, the embodiments described herein provide a TRS that is capable of managing a wide range of set point temperatures within a transport unit using a thermal accumulator or thermal accumulator module having a PCM.

In some embodiments, the TRS can include a thermal accumulator compartment storing one or more thermal accumulators having a PCM. In some embodiments, the thermal accumulator compartment can include a thermal accumulator module having a PCM.

In some embodiments, the PCM is initially charged to a solid state and then is configured to gradually change phases into a liquid state while absorbing heat flowing through air surrounding the PCM and possibly heat produced by cargo.

In some embodiments, the temperature of the cargo compartment can depend on a phase change temperature of the PCM. Also, in some embodiments, the temperature of the cargo compartment can be, at a minimum, a few degrees warmer than the phase change temperature of the PCM. Also, replacement of PCM can be very difficult and expensive. Accordingly, in some embodiments, to achieve a desired set point temperature within the cargo compartment, a PCM can be chosen with a phase change temperature that is below a lowest desired temperature within the cargo compartment.

In one embodiment, a method for air temperature control within a cargo compartment of a transport unit using a TRS that includes a thermal accumulator having a PCM provided therein is provided. The thermal accumulator is disposed in a thermal accumulator compartment and the cargo compartment is separated from the thermal accumulator compartment via a climate controlled barrier. The method includes a controller receiving, via one or more temperature sensors, temperature data within a cargo compartment of the transport unit from. The method also includes determining a temperature within the cargo compartment based on the temperature data. Also, the method includes determining a temperature stratification within the cargo compartment based on the temperature data. Further, the method includes operating the TRS in an active operation mode when the temperature within the cargo compartment is greater than a temperature set point.

In another embodiment, a refrigerated transport unit is provided. The refrigerated transport unit includes a transport unit and a TRS. The transport unit includes a cargo compartment for storing cargo and a climate controlled barrier separating the cargo compartment from a thermal accumulator compartment. The climate controlled barrier includes one or more openings configured to provide air flow communication between the cargo compartment and the thermal accumulator compartment. The TRS is configured to provide air temperature control within the cargo compartment. The TRS includes the thermal accumulator compartment including a thermal accumulator and a controller. The thermal accumulator has a phase change material (PCM) disposed therein. The controller is configured to control air flow communication between the thermal accumulator compartment and the cargo compartment so as to provide air temperature control within the cargo compartment.

An advantage of these embodiments is that air temperature control within a cargo compartment of a transport unit can be achieved with a minimal amount of energy when compared to a TRS using, for example, an active refrigeration system (e.g., a vapor-compressor type refrigeration system). That is, the energy required by the embodiments described herein can be limited to energy for adjusting a position of one or more dampers and/or adjusting a speed and operation of one or more fans.

Comments:

The following is noted with respect to the embodiments described herein.

The thermal accumulator discussed herein can include a PCM that is adaptable to heat or to cool a storage space (e.g., a cargo compartment) to a temperature suitable for the cargo stored in the storage space. The thermal accumulator can also be used for a defrost operation within the storage space.

Operation of the TRS for a refrigerated transport unit can be independent to various thermal loads that occur due to external conditions external the refrigerated transport unit. That is, the thermal accumulator of the TRS can maintain a desired temperature within the storage space of the refrigerated transport unit regardless of external conditions outside of the refrigerated transport unit.

The PCM used in the thermal accumulator can be any fluid which has a solid-liquid transition point in a rage between about −32° C. and about 0° C. The PCM can be compatible with metals, for example, aluminum. The PCM can store heat in a transition phase using a latent heat (e.g., heat of fusion). The PCM can store heat in a liquid phase. The PCM can have a phase transition temperature that absorbs changes in temperature of the refrigerated transport unit.

The thermal accumulator allows a transfer of heat from the PCM to an air space within the storage space and vice versa. The heat exchanger can include a single, dual, or multiple pass design. The thermal accumulator can use a natural or forced convection to facilitate heat exchange between the PCM and an air space within the storage space. In some embodiments, the thermal accumulator can include a wall or walls with a substantially flat surface and a wall or walls with at least a partially enhanced (e.g., ribbed surface). The thermal accumulator can store a PCM and/or include an empty or free expansion space within the thermal accumulator.

In some embodiments, a thermal accumulator compartment storing a thermal accumulator can be retrofitted into/onto a refrigerated transport unit. The thermal accumulator compartment can be installed to the refrigerated transport unit without specialized equipment. In some embodiments, the thermal accumulator compartment can be designed such that the weight of the thermal accumulator compartment can be supported by a floor, one or more side walls or a ceiling of the refrigerated transport unit. In some embodiments, the PCM can be provided in the thermal accumulator from the top.

The TRS can provide a defrost operation. In some embodiments, a second fluid or refrigerant may be used to perform a defrost operation. In some embodiments, the TRS can include an optional defrost device (e.g., heating bar(s), heating sheet(s), heating tube(s), etc.) for performing the defrost operation. In some embodiments, the thermal accumulator can include a second fluid or refrigerant line to perform the defrost operation. In some embodiments, the defrost operation can be performed in less than 24 hours.

In some embodiments, the TRS can include one or more fans. The power of the fans can be adjusted based on a temperature within the storage space. The fans can provide an air flow rate sufficient to reach a desired amount of heat transfer from the PCM in the thermal accumulator to an air space within the storage space and vice versa. The fans can be controlled/adjusted based on a desired set point temperature within the storage space.

BRIEF DESCRIPTION OF THE DRAWINGS

References are made to the accompanying drawings that form a part of this disclosure and which illustrate the embodiments in which the systems and methods described in this Specification can be practiced.

FIG. 1 illustrates a transport refrigeration system (TRS) for a refrigerated transport unit, according to some embodiments.

FIG. 2 illustrates a side interior view of a transport unit and a TRS using a thermal accumulator compartment, according to one embodiment.

FIG. 3 illustrates a side interior view of a transport unit and a TRS using a thermal accumulator compartment provided within the transport unit, according to another embodiment.

FIG. 4 illustrates a flow chart of a method for air temperature control within a cargo compartment, according to one embodiment.

Like reference numbers represent like parts throughout.

DETAILED DESCRIPTION

Embodiments of this disclosure relate generally to a transport refrigeration system (TRS) including a thermal accumulator or thermal accumulator module having a phase change material (PCM). More specifically, the embodiments relate to air temperature control of a TRS with a thermal accumulator or thermal accumulator module having a PCM.

That is, the embodiments described herein provide a TRS that is capable of managing a wide range of set point temperatures within a transport unit having a thermal accumulator or thermal accumulator module.

A suitable thermal accumulator or thermal accumulator module is described in U.S. patent application Ser. No. 14/268,239 (Attorney Docket 20420.0140US01), filed on May 2, 2014, and titled “Thermal Accumulator for a Transport Refrigeration System,” which is incorporated herein by reference in its entirety.

A TRS is generally used to control an environmental condition such as, but not limited to, temperature, humidity, and air quality of a transport unit. Examples of transport units include, but are not limited to, a container on a flat car, an intermodal container, a truck, a boxcar, or other similar transport unit (generally referred to as a “transport unit”). Embodiments of this disclosure may be used in any suitable transport unit such as those listed above.

A “transport refrigeration system” (TRS) includes, for example, a refrigeration system for controlling the refrigeration of an interior space of a refrigerated transport unit. The TRS may be a vapor-compressor type refrigeration system, a thermal accumulator type system, or any other suitable refrigeration system that can use refrigerant, cold plate technology, or the like.

A “refrigerated transport unit” includes, for example, a transport unit having a TRS. A refrigerated transport unit can be used to transport perishable items such as, but not limited to, produce, frozen foods, and meat products.

A “phase change material” (PCM) includes, for example, a material that can store or release a large amount of energy upon a phase change (e.g., from a solid to a liquid, a liquid to a solid, etc.) while remaining at about a constant temperature. A PCM can gradually absorb heat (e.g., from an interior space of a refrigerated transport unit, etc.) while remaining at about a constant temperature during a phase transformation from a solid state into a liquid state. A PCM can, for example, be used to maintain an interior space of a refrigerated transport unit at a desired temperature.

An “aluminum compatible PCM” includes, for example, a PCM that is not corrosive to aluminum. Examples of aluminum compatible PCMs include, but are not limited to, a mixture of hydrogen peroxide and water, a propylene glycol and water mixture, and the like.

The TRS can include one or more thermal accumulators and/or thermal accumulator modules. Embodiments described herein include thermal accumulators and thermal accumulator modules having a PCM contained therein. The thermal accumulators and thermal accumulator modules can be replaceable and rechargeable outside of the refrigerated transport unit. In some embodiments, this can reduce an amount of time in which the refrigerated transport unit is idle. In some embodiments, this can reduce the weight of the refrigerated transport unit as a TRU may not be part of the system.

In some configurations, the TRS can also include an active transport refrigeration unit (TRU) (e.g., a TRU having a compressor, a condenser, an expansion valve and an evaporator all connected via a refrigerant circuit). In configurations where the TRS also includes an active TRU, the thermal accumulator and/or thermal accumulator module may allow the TRU to be disabled for a period of time while still maintaining the desired environmental condition. Also, in some embodiments of these configurations, the TRU can be removable and the environmental condition can be controlled using the thermal accumulator and/or the thermal accumulator module.

FIG. 1 illustrates a TRS 100 for a transport unit 105. The transport unit 105 includes a thermal accumulator compartment 110 and an insulated cargo compartment 120 separated by a climate controlled barrier 115. The thermal accumulator compartment 110 includes a thermal accumulator module 113. In some embodiments, the thermal accumulator module 113 can include a plurality of thermal accumulators (not shown) each containing a PCM (not shown). In some embodiments, the thermal accumulator module 113 can be replaced with one or more discrete thermal accumulators (not shown) containing a PCM (not shown). Also, in some embodiments, the thermal accumulator compartment 110 can also be configured to store cargo that is to be kept frozen such as, for example, frozen food.

While FIG. 1 shows the thermal accumulator compartment 110 located at one end within the transport unit 105, in other embodiments, the thermal accumulator compartment 110 can be attached to or located outside of the transport unit 105 (see FIG. 2).

The climate controlled barrier 115 includes a plurality of openings 117 and a plurality of adjustable dampers 119 for opening and closing the openings 117. The adjustable dampers 119 are configured to provide air flow communication between the thermal accumulator compartment 110 and the insulated cargo compartment 120. The adjustable dampers 119 can be controlled by a programmable TRS controller 130 to any position between a fully closed position to a fully open position. In one embodiment, the fully closed position can be a position in which one of the plurality of dampers 119 prevents any air flow communication between the thermal accumulator compartment 110 and the insulated cargo compartment 120. In one embodiment, the fully open position can be a position in which one of the plurality of dampers 119 does not interfere with any air flow communication between the thermal accumulator compartment 110 and the insulated cargo compartment 120.

While FIG. 1 shows two openings 117 and two adjustable dampers 119, it is appreciated that in other embodiments the climate controlled barrier can include, for example, one opening and one damper or three or more openings and three or more corresponding dampers. Also, in some embodiments, the number of openings 117 can be greater than the number of dampers 119 with one or more of the openings 117 being a free opening without a corresponding damper allowing for air flow communication between the thermal accumulator compartment 110 and the insulated cargo compartment 120 without any interference.

The insulated cargo compartment 120 can be configured, for example, to store a cargo including, for example, perishable items such as, but not limited to, produce and meat products. The insulated cargo compartment 120 also includes a plurality of sensors 125 that are configured to provide temperature readings at various locations within the insulated cargo compartment 120. In some embodiments, the sensors 125 can be located at portions of the insulated cargo compartment 120 known to be warmer and cooler than an average temperature within the insulated cargo compartment 120 so as to determine a temperature stratification within the insulated cargo compartment. It will be appreciated that the number and location of the sensors 125 can vary as required to obtain a desired precision in determining the temperature stratification within the insulated cargo compartment 120.

Also, in some embodiments, the insulated cargo compartment 120 can include one or more fans (not shown) that can be used with the adjustable dampers 119 to facilitate air flow communication between the thermal accumulator compartment 110 and the insulated cargo compartment 120. In some embodiments, the one or more fans can be variable speed fans and the speed of the fans can be varied based on air temperature requirements within the insulated cargo compartment 120. Further, the insulated cargo compartment 120 can also include an optional heating device 135.

Referring back to the thermal accumulator compartment 110, the PCM stored therein is configured to have a phase change temperature that is lower than a desired set point temperature within the insulated cargo compartment 120. The PCM can be initially charged to a solid state and then can be configured to gradually change phases into a liquid state while absorbing heat flowing through air surrounding the PCM and possibly heat produced by cargo stored in the thermal accumulator compartment 110. Accordingly, by controlling operation of one or more of the dampers 119 and/or one or more fans, the TRS 100 can control the amount of air cooled by the PCM that enters the insulated cargo compartment 120. Thus, the TRS 100 can achieve a variety of set point temperatures within the insulated cargo compartment 120 without having to replace the PCM.

As discussed above, the TRS 100 can also include the programmable TRS controller 130 that can be configured to, among other functions, control a temperature within the insulated cargo compartment 120. This can include controlling a position of the adjustable dampers 119 and/or operation and speed of one or more fans. The TRS controller 130 may include a single integrated control unit or may include a distributed network of TRS control elements. The number of distributed control elements in a given network can depend upon the particular application. While the TRS controller 130 is located in the insulated cargo compartment 120, it is appreciated that in other embodiments, the TRS controller 130 can be located in different areas including, for example, the thermal accumulator compartment 110 or outside of the transport unit 105.

It is also appreciated that in some embodiments the TRS 100 may also include a TRU attached to one side of transport unit 105. In such embodiments, refrigeration within the insulated cargo compartment 120 can also be controlled, for example by a refrigeration circuit that includes a compressor, a condenser, an evaporator and an expansion valve. When the TRS 100 includes a TRU, it is appreciated that in some embodiments the TRS controller 130 can be located in the TRU 105.

Also, in some embodiments, the insulated cargo compartment can be divided into a plurality of zones (not shown). Each zone can be controlled by the TRS 100 to be at a different temperature.

Further, as shown in FIG. 1, in some embodiments, the TRS 100 also includes an optional heating device 135 configured to provide heating to the insulated cargo compartment 120. The optional heating device 135 can be used, for example, when the temperature inside the insulated cargo compartment 120 is below the desired set point temperature within the insulated cargo compartment 120. In some embodiments, the optional heating device 135 can be an integrated part of the TRS 100. In other embodiments, the optional heating device 135 can be separate from the TRS 100 or removable from the TRS 100 for, e.g., seasonal operation. The optional heating device 135 can include one or more electric heating rods provided outside of the thermal accumulator compartment. In some embodiments, the optional heating device 135 can be used with one or more fans within the insulated cargo compartment 120 to distribute heat generated by the optional heating device 135 throughout the insulated cargo compartment 120. In some embodiments, the TRS controller 130 can be configured to activate the optional heating device 135 (and one or more fans) when the temperature within the insulated cargo compartment 120 is below the desired set point temperature. Once the desired set point temperature is reached, the TRS controller 130 can deactivate the optional heating device 135 (and the one or more fans).

FIG. 2 illustrates a side interior view of a transport unit 205 and a TRS 200 using a thermal accumulator compartment 210, according to one embodiment. The thermal accumulator compartment 210 is attached to a wall 207 of the transport unit 205. The transport unit 205 includes a cargo compartment 220 and an insulated portion 216, surrounding the cargo compartment 220, that together form an insulated cargo compartment 222.

The thermal accumulator compartment 210 includes a thermal accumulator 212 provided along an interior circumference of the thermal accumulator compartment 210. Accordingly, the thermal accumulator compartment 210 can be configured to store a cargo (not shown) at a temperature colder than the temperature of the cargo compartment 220.

The cargo compartment 220 stores a cargo 240 and also includes a plurality of sensors 225. The cargo 240 can include, for example, perishable items such as, but not limited to, produce and meat products.

The plurality of sensors 225 are configured to provide temperature readings at various locations within the cargo compartment 220. In some embodiments, the sensors 225 can be located at portions of the cargo compartment 220 known to be warmer and cooler than an average temperature within the cargo compartment 220 so as to determine a temperature stratification within the insulated cargo compartment. It will be appreciated that the number and location of the sensors 225 can vary as required to obtain a desired precision in determining the temperature stratification within the cargo compartment 220.

A plurality of openings 217 created on the wall 207 and a wall 214 of the thermal accumulator compartment 210 provide air flow communication between the thermal accumulator compartment 210 and the cargo compartment 220. That is, the wall 207 and the wall 214 together form a climate controlled barrier 215. A plurality of adjustable dampers 219 are provided for opening and closing the openings 217. The adjustable dampers 219 are configured to control the amount of air flow communication between the thermal accumulator compartment 210 and the cargo compartment 220. It is appreciated that in some embodiments, the cargo compartment 220 can also include one or more fans to help facilitate air temperature control within the cargo compartment 220.

The adjustable dampers 219 can be controlled by a TRS controller 230 to any position between a fully closed position to a fully open position. In one embodiment, the fully closed position can be a position in which one of the plurality of dampers 219 prevents any air flow communication between the thermal accumulator compartment 210 and the cargo compartment 220. In one embodiment, the fully open position can be a position in which one of the plurality of dampers 219 does not interfere with any air flow communication between the thermal accumulator compartment 210 and the insulated cargo compartment 220.

While FIG. 2 shows four openings 217 and four adjustable dampers 219, it is appreciated that in other embodiments the climate controlled barrier can include, for example, one to three openings and one to three dampers or five or more openings and five or more corresponding dampers. Also, in some embodiments, the number of openings 217 can be greater than the number of dampers 219 with one or more of the openings 217 being a free opening without a corresponding damper allowing for air flow communication between the thermal accumulator compartment 210 and the cargo compartment 220 without any interference.

Also, in some embodiments, the cargo compartment 220 can include one or more fans that can be used with the adjustable dampers 219 to facilitate air flow communication between the thermal accumulator compartment 210 and the cargo compartment 220. In some embodiments, the one or more fans can be variable speed fans and the speed of the fans can be varied based on air temperature requirements within the cargo compartment 220.

As shown by arrows 250, when the dampers 219 are in an open position, air from the thermal accumulator compartment 210 is configured to pass through the openings 217 and surround the cargo 240.

Referring back to the thermal accumulator 212, in some embodiments, the PCM stored therein is configured to have a phase change temperature that is lower than a desired set point temperature within the cargo compartment 220. The PCM can be initially charged to a solid state and then can be configured to gradually change phases into a liquid state while absorbing heat flowing through air surrounding the PCM and possibly heat produced by cargo stored in the thermal accumulator compartment 210. Accordingly, by controlling operation of one or more of the dampers 219 and/or one or more fans, the TRS 200 can control the amount of air cooled by the PCM that enters the cargo compartment 220. Thus, the TRS 200 can achieve a variety of set point temperatures within the cargo compartment 220 without having to replace the PCM.

The programmable TRS controller 230 can be configured to, among other functions, control a temperature within the cargo compartment 220. This can include controlling a position of the adjustable dampers 219 and/or operation and speed of one or more fans. The TRS controller 230 may include a single integrated control unit or may include a distributed network of TRS control elements. The number of distributed control elements in a given network can depend upon the particular application. While the TRS controller 230 is located in the cargo compartment 220, it is appreciated that in other embodiments, the TRS controller 230 can be located in different areas including, for example, the thermal accumulator compartment 210 or outside of the transport unit 205.

FIG. 3 illustrates a side interior view of a transport unit 305 with a TRS 300 using a thermal accumulator compartment 310 provided within the transport unit 305, according to another embodiment. The thermal accumulator compartment 310 is provided at one end of the transport unit 305. The transport unit 305 also includes a cargo compartment 320 and an insulated portion 316 surrounding the cargo compartment 320 and the thermal accumulator compartment 310.

The thermal accumulator compartment 310 includes wall 315 that acts as a climate controlled barrier to separate the thermal accumulator compartment from the surrounding cargo compartment 320. The thermal accumulator compartment 310 also includes a thermal accumulator 312 provided along an interior side of the wall 315. Accordingly, the thermal accumulator compartment 310 can be configured to store a cargo (not shown) at a temperature colder than the temperature of the cargo compartment 320.

The cargo compartment 320 stores a cargo 340 and also includes a plurality of sensors 325 and a fan 360. The cargo 340 can include, for example, perishable items such as, but not limited to, produce and meat products.

The plurality of sensors 325 are configured to provide temperature readings at various locations within the cargo compartment 320. In some embodiments, the sensors 325 can be located at portions of the cargo compartment 320 known to be warmer and cooler than an average temperature within the cargo compartment 320 so as to determine a temperature stratification within the insulated cargo compartment. It will be appreciated that the number and location of the sensors 325 can vary as required to obtain a desired precision in determining the temperature stratification within the cargo compartment 320.

The fan 360 is configured to facilitate air flow communication between the thermal accumulator compartment 310 and the cargo compartment 320. In some embodiments, the fan 360 can be a variable speed fan and the speed of the fan 360 can be varied based on air temperature requirements within the cargo compartment 320.

The wall 315 includes a plurality of openings 317 a, 317 b (referred together as the openings 317) and a plurality of adjustable dampers 319 a, 319 b (referred together as the adjustable dampers 319) for opening and closing the openings 317. The adjustable dampers 319 are configured to provide air flow communication between the thermal accumulator compartment 310 and the cargo compartment 320. The adjustable dampers 319 can be controlled by a programmable TRS controller 330 to any position between a fully closed position to a fully open position. In one embodiment, the fully closed position can be a position in which one of the plurality of dampers 319 prevents any air flow communication between the thermal accumulator compartment 310 and the cargo compartment 320. In one embodiment, the fully open position can be a position in which one of the plurality of dampers 319 does not interfere with any air flow communication between the thermal accumulator compartment 310 and the cargo compartment 320.

While FIG. 3 shows two openings 317 and two adjustable dampers 319, it is appreciated that in other embodiments the wall 315 can include, for example, two or less openings and two or less dampers or three or more openings and three or more corresponding dampers. Also, in some embodiments, the number of openings 317 can be greater than the number of dampers 319 with one or more of the openings 317 being a free opening without a corresponding damper allowing for air flow communication between the thermal accumulator compartment 310 and the cargo compartment 320 without any interference.

As shown by arrows 350, when the dampers 319 are in an open position and the fan 360 is in operation, air from the thermal accumulator compartment 310 is directed out of the opening 317 a into the cargo compartment 320. The air then passes around the cargo 340 and back into the thermal accumulator compartment 310.

Referring back to the thermal accumulator 312, in some embodiments, the PCM stored therein is configured to have a phase change temperature that is lower than a desired set point temperature within the cargo compartment 320. The PCM can be initially charged to a solid state and then can be configured to gradually change phases into a liquid state while absorbing heat flowing through air surrounding the PCM and possibly heat produced by cargo stored in the thermal accumulator compartment 310. Accordingly, by controlling operation of one or more of the dampers 319 and/or the fan 360, the TRS 300 can control the amount of air cooled by the PCM that enters the insulated cargo compartment 320. Thus, the TRS 300 can achieve a variety of set point temperatures within the cargo compartment 320 without having to replace the PCM.

The programmable TRS controller 330 can be configured to, among other functions, control a temperature within the cargo compartment 220. This can include controlling a position of the adjustable dampers 319 and/or operation and speed of one or more fans. The TRS controller 330 may include a single integrated control unit or may include a distributed network of TRS control elements. The number of distributed control elements in a given network can depend upon the particular application. While the TRS controller 330 is located in the cargo compartment 320, it is appreciated that in other embodiments, the TRS controller 330 can be located in different areas including, for example, the thermal accumulator compartment 310 or outside of the transport unit 305.

FIG. 4 illustrates a flow chart of a method 400 for air temperature control within a cargo compartment (e.g., the cargo compartments 120, 220, 320) using a TRS (e.g., the TRSs 100, 200, 300), according to one embodiment. In some embodiments, the method 400 can be performed, for example, at a periodic rate (e.g., every second, every five minutes, every hour, etc.), a change in operation mode of the TRS, upon user instruction, etc.

At 405, a controller (such as the TRS controllers 130, 230, 330) is configured to obtain temperature data within the cargo compartment from one or more sensors within the cargo compartment.

At 410, the controller determines a temperature within the cargo compartment based on the temperature data obtained by the one or more sensors. In some embodiments, the temperature within the cargo compartment is determined by calculating an average temperature based on the temperature data obtained by the one or more sensors.

At 415, the controller determines a temperature stratification within the cargo compartment based on the temperature data by the one or more sensors. In some embodiments, the temperature stratification can be determined by subtracting a highest temperature reading of the temperature data from lowest temperature reading of the temperature data.

It is appreciated that in some embodiments the controller can determine the temperature at 410 and the temperature stratification 415 within the cargo compartment concurrently. In other embodiments, the controller can determine the temperature at 410 and then the temperature stratification 415 or vice versa.

At 420, the controller determines whether the temperature within the cargo compartment determined at 410 is at or below a temperature set point. The set point temperature can be, for example, a desired temperature to preserve cargo stored within the cargo compartment. The temperature set point can be set based on user requirements and/or cargo stored in the cargo compartment. Also, the temperature set point can be, for example, a user defined set point stored in a memory portion of the controller. If the temperature set point has not been reached, the method proceeds to 425. If the temperature set point has been reached, the method 400 proceeds to 430.

At 425, the controller operates the TRS in an active operation mode in order, for example, to allow the temperature within the cargo compartment to reach temperature set point. In some embodiments, the active operation mode can include opening one or more adjustable dampers (e.g., the dampers 119, 219, 319) to a required opening position to allow air from a thermal accumulator compartment to enter the cargo compartment. Accordingly, air from the thermal accumulator compartment can blend with air in the cargo compartment so as to reduce the temperature within the cargo compartment. In some embodiments, during the active operation mode, the controller can adjust the opening position of the adjustable dampers to, for example, allow the cargo compartment to reach the temperature set point as quickly as possible.

Also, in some embodiments, when the TRS includes one or more fans, the active operation mode can also include operating the one or more fans (e.g., the fan 360) to help facilitate air from the thermal accumulator compartment entering the cargo compartment. Also, when the one or more fans are variable speed fans, the controller can vary the speed of the one or more fans during the active operation mode. For example, the controller can reduce the speed of the one or more fans to minimize energy consumption and reduce heat dissipated by the one or more fans. The controller can also increase the speed of the one or more fans during the active operation mode to increase the speed in which the cargo compartment reaches the temperature set point. The method 400 then proceeds back to 405.

At 430, the controller determines whether the temperature stratification within the cargo compartment obtained at 415 is within a stratification threshold range. The stratification threshold range can be set based on user requirements and/or cargo stored in the cargo compartment. Also, the stratification threshold range can be, for example, a user defined set point stored in a memory portion of the controller. For example, in some embodiments, the stratification threshold range can be 2° C. In other embodiments, the stratification threshold range can be 10° C. If the controller determines that the temperature stratification within the cargo compartment is within the stratification threshold range, the method 400 proceeds to 435. If the controller determines that the temperature stratification within the cargo compartment is not within the stratification threshold range, the method 400 proceeds to 440.

At 435, the controller operates the TRS in a standby operation mode. In some embodiments, the standby operation mode can include closing one or more adjustable dampers to a required closing position to prevent air from the thermal accumulator compartment to enter the cargo compartment. Also, in some embodiments, the standby operation mode can also include stopping operating of one or more fans. Accordingly, the standby operation mode can allow the TRS to consume little or no energy. The standby operation mode can also be used to delay cooling within the cargo compartment. The method 400 then proceeds back to 405.

At 440, the controller operates the TRS in a temperature unification mode. In some embodiments, the temperature unification mode can include closing one or more adjustable dampers to a required closing position to prevent air from the thermal accumulator compartment to enter the cargo compartment. Also, in some embodiments, when the TRS includes one or more fans, the temperature unification mode can include operating one or more fans to help facilitate air flow within the cargo compartment. Accordingly, air in the cargo compartment can be mixed to allow for a more unified temperature distribution within the cargo compartment.

Also, the controller can vary the speed of the one or more fans during the temperature unification mode. For example, the controller can reduce the speed of the one or more fans to minimize energy consumption and reduce heat dissipated by the one or more fans. The controller can also increase the speed of the one or more fans during the temperature unification mode to increase the speed of temperature unification within the cargo compartment. The method 400 then proceeds back to 405.

An advantage of these embodiments is that air temperature control within a cargo compartment of a transport unit can be achieved with a minimal amount of energy when compared to a TRS using, for example, an active refrigeration system (e.g., a vapor-compressor type refrigeration system). That is, the energy required by the embodiments described herein can be limited to energy for adjusting a position of one or more dampers and/or adjusting a speed and operation of one or more fans.

Aspects

It is noted that any of aspects 1-9 and 10-22 can be combined.

-   Aspect 1. A method for air temperature control within a cargo     compartment of a transport unit using a transport refrigeration     system (TRS) that includes a thermal accumulator having a phase     change material (PCM) provided therein, the thermal accumulator     being disposed in a thermal accumulator compartment, and the cargo     compartment being separated from the thermal accumulator compartment     via a climate controlled barrier, the method comprising:

a controller receiving, via one or more temperature sensors, temperature data within a cargo compartment of the transport unit from;

determining a temperature within the cargo compartment based on the temperature data;

determining a temperature stratification within the cargo compartment based on the temperature data;

operating the TRS in an active operation mode when the temperature within the cargo compartment is greater than a temperature set point.

-   Aspect 2. The method according to aspect 1, wherein operating the     TRS in the active operation mode includes:

opening one or more adjustable dampers disposed at one or more openings of the climate controlled barrier to an open position; and

directing air from the thermal accumulator compartment through the one or more openings of the climate controlled barrier into the cargo compartment.

-   Aspect 3. The method according to any of aspects 1-2, wherein     operating the TRS in the active operation mode includes:

operating one or more fans adjacent to one or more openings of the climate controlled barrier; and

directing air, via the one or more fans, from the thermal accumulator compartment through the one or more openings of the climate controlled barrier into the cargo compartment.

-   Aspect 4. The method according to any of aspects 1-3, further     comprising:

operating the TRS in a temperature unification mode when the temperature stratification is outside of a stratification threshold range and the temperature within the cargo compartment is less than or equal to the temperature set point.

-   Aspect 5. The method according to aspect 4, wherein operating the     TRS in the temperature unification mode includes:

closing one or more adjustable dampers disposed at one or more openings of the climate controlled barrier to a closed position; and

distributing air within the cargo compartment to reduce temperature stratification within the cargo compartment.

-   Aspect 6. The method according to any of aspects 4-5, wherein     operating the TRS in the temperature unification mode includes: -   operating one or more fans within the cargo compartment; and

distributing air, via the one or more fans, within the cargo compartment to reduce temperature stratification within the cargo compartment.

-   Aspect 7. The method according to any of aspects 1-6, further     comprising:     -   operating the TRS in a standby operation mode when the         temperature stratification is within the stratification         threshold range and the temperature within the cargo compartment         is less than or equal to the temperature set point. -   Aspect 8. The method according to aspect 7, wherein operating the     TRS in the standby operation mode includes:

closing one or more adjustable dampers disposed at one or more openings of the climate controlled barrier to a closed position.

-   Aspect 9. The method according to any of aspects 7-8, wherein     operating the TRS in the standby operation mode includes:

stopping operation of one or more fans within the cargo compartment.

-   Aspect 10. A refrigerated transport unit comprising:

a transport unit including:

-   -   a cargo compartment for storing cargo, and     -   a climate controlled barrier separating the cargo compartment         from a thermal accumulator compartment, the climate controlled         barrier including one or more openings configured to provide air         flow communication between the cargo compartment and the thermal         accumulator compartment; and

a transport refrigeration system (TRS) configured to provide air temperature control within the cargo compartment, the TRS including:

-   -   the thermal accumulator compartment including a thermal         accumulator, the thermal accumulator having a phase change         material (PCM) disposed therein, and     -   a controller configured to control air flow communication         between the thermal accumulator compartment and the cargo         compartment so as to provide air temperature control within the         cargo compartment.

-   Aspect 11. The refrigerated transport unit of aspect 10, further     comprising one or more adjustable dampers disposed on the climate     controlled barrier, wherein the dampers are configured to control an     amount of air flow through the one or more openings between the     cargo compartment and the thermal accumulator compartment,

wherein the controller is configured to control an opening position of the one or more adjustable dampers to control the amount of air flow through the one or more openings between the cargo compartment and the thermal accumulator compartment to control a temperature within the cargo compartment.

-   Aspect 12. The refrigerated transport unit of any of aspects 10-11,     further comprising one or more fans configured to at least one of:

direct air from the thermal accumulator module to the cargo compartment via the one or more openings to control a temperature within the cargo compartment, and

distribute air within the cargo compartment to reduce temperature stratification within the cargo compartment.

-   Aspect 13. The refrigerated transport unit of aspect 12, wherein the     one or more fans is a variable speed fan, and the controller is     configured to control a speed of the variable speed fan. -   Aspect 14. The refrigerated transport unit of any of aspects 10-13,     further comprising one or more sensors configured to provide     temperature measurements at one or more locations within the cargo     compartment. -   Aspect 15. The refrigerated transport unit of any of aspects 10-14,     wherein the thermal accumulator compartment is disposed within the     transport unit. -   Aspect 16. The refrigerated transport unit of any of aspects 10-14,     wherein the thermal accumulator compartment is attached to a side     wall of the transport unit. -   Aspect 17. The refrigerated transport unit of any of aspects 10-16,     wherein, when a temperature within the cargo compartment is greater     than a temperature set point, the controller is configured to:

open one or more adjustable dampers disposed at the one or more openings of the climate controlled barrier to an open position to direct air from the thermal accumulator compartment through the one or more openings of the climate controlled barrier into the cargo compartment.

-   Aspect 18. The refrigerated transport unit of any of aspects 10-17,     wherein, when a temperature within the cargo compartment is greater     than a temperature set point, the controller is configured to:

operate one or more fans adjacent to the one or more openings of the climate controlled barrier to direct air from the thermal accumulator compartment through the one or more openings of the climate controlled barrier into the cargo compartment.

-   Aspect 19. The refrigerated transport unit of any of aspects 10-18,     wherein, when a temperature stratification is outside of a     stratification threshold range and a temperature within the cargo     compartment is less than or equal to a temperature set point, the     controller is configured to:

close one or more adjustable dampers disposed at the one or more openings of the climate controlled barrier to a closed position to reduce temperature stratification within the cargo compartment.

-   Aspect 20. The refrigerated transport unit of any of aspects 10-19,     wherein, when a temperature stratification is outside of a     stratification threshold range and a temperature within the cargo     compartment is less than or equal to a temperature set point, the     controller is configured to:

operate one or more fans to distribute air within the cargo compartment to reduce temperature stratification within the cargo compartment.

-   Aspect 21. The refrigerated transport unit of any of aspects 10-20,     wherein, when a temperature stratification is within a     stratification threshold range and a temperature within the cargo     compartment is less than or equal to a temperature set point, the     controller is configured to:

close one or more adjustable dampers disposed at one or more openings of the climate controlled barrier to a closed position.

-   Aspect 22. The refrigerated transport unit of any of aspects 10-20,     wherein, when a temperature stratification is within a     stratification threshold range and a temperature within the cargo     compartment is less than or equal to a temperature set point, the     controller is configured to:

stop operation of one or more fans within the cargo compartment.

The terminology used in this Specification is intended to describe particular embodiments and is not intended to be limiting. The terms “a,” “an,” and “the” include the plural forms as well, unless clearly indicated otherwise. The terms “comprises” and/or “comprising,” when used in this Specification, specify the presence of the stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, and/or components.

With regard to the preceding description, it is to be understood that changes may be made in detail, especially in matters of the construction materials employed and the shape, size, and arrangement of parts without departing from the scope of the present disclosure. The word “embodiment” as used within this Specification may, but does not necessarily, refer to the same embodiment. This Specification and the embodiments described are exemplary only. Other and further embodiments may be devised without departing from the basic scope thereof, with the true scope and spirit of the disclosure being indicated by the claims that follow. 

1. A method for air temperature control within a cargo compartment of a transport unit using a transport refrigeration system (TRS) that includes a thermal accumulator having a phase change material (PCM) provided therein, the thermal accumulator being disposed in a thermal accumulator compartment, and the cargo compartment being separated from the thermal accumulator compartment via a climate controlled barrier, the method comprising: a controller receiving, via one or more temperature sensors, temperature data within a cargo compartment of the transport unit from; determining a temperature within the cargo compartment based on the temperature data; determining a temperature stratification within the cargo compartment based on the temperature data; operating the TRS in an active operation mode when the temperature within the cargo compartment is greater than a temperature set point.
 2. The method according to claim 1, wherein operating the TRS in the active operation mode includes: opening one or more adjustable dampers disposed at one or more openings of the climate controlled barrier to an open position; and directing air from the thermal accumulator compartment through the one or more openings of the climate controlled barrier into the cargo compartment.
 3. The method according to claim 1, wherein operating the TRS in the active operation mode includes: operating one or more fans adjacent to one or more openings of the climate controlled barrier; and directing air, via the one or more fans, from the thermal accumulator compartment through the one or more openings of the climate controlled barrier into the cargo compartment.
 4. The method according to claim 1, further comprising: operating the TRS in a temperature unification mode when the temperature stratification is outside of a stratification threshold range and the temperature within the cargo compartment is less than or equal to the temperature set point.
 5. The method according to claim 4, wherein operating the TRS in the temperature unification mode includes: closing one or more adjustable dampers disposed at one or more openings of the climate controlled barrier to a closed position; and distributing air within the cargo compartment to reduce temperature stratification within the cargo compartment.
 6. The method according to claim 4, wherein operating the TRS in the temperature unification mode includes: operating one or more fans within the cargo compartment; and distributing air, via the one or more fans, within the cargo compartment to reduce temperature stratification within the cargo compartment.
 7. The method according to claim 1, further comprising: operating the TRS in a standby operation mode when the temperature stratification is within the stratification threshold range and the temperature within the cargo compartment is less than or equal to the temperature set point.
 8. The method according to claim 7, wherein operating the TRS in the standby operation mode includes: closing one or more adjustable dampers disposed at one or more openings of the climate controlled barrier to a closed position.
 9. The method according to claim 7, wherein operating the TRS in the standby operation mode includes: stopping operation of one or more fans within the cargo compartment.
 10. A refrigerated transport unit comprising: a transport unit including: a cargo compartment for storing cargo, and a climate controlled barrier separating the cargo compartment from a thermal accumulator compartment, the climate controlled barrier including one or more openings configured to provide air flow communication between the cargo compartment and the thermal accumulator compartment; and a transport refrigeration system (TRS) configured to provide air temperature control within the cargo compartment, the TRS including: the thermal accumulator compartment including a thermal accumulator, the thermal accumulator having a phase change material (PCM) disposed therein, and a controller configured to control air flow communication between the thermal accumulator compartment and the cargo compartment so as to provide air temperature control within the cargo compartment.
 11. The refrigerated transport unit of claim 10, further comprising one or more adjustable dampers disposed on the climate controlled barrier, wherein the dampers are configured to control an amount of air flow through the one or more openings between the cargo compartment and the thermal accumulator compartment, wherein the controller is configured to control an opening position of the one or more adjustable dampers to control the amount of air flow through the one or more openings between the cargo compartment and the thermal accumulator compartment to control a temperature within the cargo compartment.
 12. The refrigerated transport unit of claim 10, further comprising one or more fans configured to at least one of: direct air from the thermal accumulator module to the cargo compartment via the one or more openings to control a temperature within the cargo compartment, and distribute air within the cargo compartment to reduce temperature stratification within the cargo compartment.
 13. The refrigerated transport unit of claim 12, wherein the one or more fans is a variable speed fan, and the controller is configured to control a speed of the variable speed fan.
 14. The refrigerated transport unit of claim 10, further comprising one or more sensors configured to provide temperature measurements at one or more locations within the cargo compartment.
 15. The refrigerated transport unit of claim 10, wherein the thermal accumulator compartment is disposed within the transport unit.
 16. The refrigerated transport unit of claim 10, wherein the thermal accumulator compartment is attached to a side wall of the transport unit.
 17. The refrigerated transport unit of claim 10, wherein, when a temperature within the cargo compartment is greater than a temperature set point, the controller is configured to: open one or more adjustable dampers disposed at the one or more openings of the climate controlled barrier to an open position to direct air from the thermal accumulator compartment through the one or more openings of the climate controlled barrier into the cargo compartment.
 18. The refrigerated transport unit of claim 10, wherein, when a temperature within the cargo compartment is greater than a temperature set point, the controller is configured to: operate one or more fans adjacent to the one or more openings of the climate controlled barrier to direct air from the thermal accumulator compartment through the one or more openings of the climate controlled barrier into the cargo compartment.
 19. The refrigerated transport unit of any of claim 10, wherein, when a temperature stratification is outside of a stratification threshold range and a temperature within the cargo compartment is less than or equal to a temperature set point, the controller is configured to: close one or more adjustable dampers disposed at the one or more openings of the climate controlled barrier to a closed position to reduce temperature stratification within the cargo compartment.
 20. The refrigerated transport unit of claim 10, wherein, when a temperature stratification is outside of a stratification threshold range and a temperature within the cargo compartment is less than or equal to a temperature set point, the controller is configured to: operate one or more fans to distribute air within the cargo compartment to reduce temperature stratification within the cargo compartment.
 21. The refrigerated transport unit of claim 10, wherein, when a temperature stratification is within a stratification threshold range and a temperature within the cargo compartment is less than or equal to a temperature set point, the controller is configured to: close one or more adjustable dampers disposed at one or more openings of the climate controlled barrier to a closed position.
 22. The refrigerated transport unit of claim 10, wherein, when a temperature stratification is within a stratification threshold range and a temperature within the cargo compartment is less than or equal to a temperature set point, the controller is configured to: stop operation of one or more fans within the cargo compartment. 